GATEWAYS update Day 6

A full day’s work in Dunmanus Bay collected more ground truthing information on superficial sediment distributions (continuation of the grab sample programme). Only a restricted area along the southern margin of the Bay (downwind at present) remains to be sampled. See image below for the track over the last two days (in from the shelf, a day at port, then into Dunmanus Bay – where the CV is now (1300hrs 27/04/2012) ):

A resurvey of the outer part of the Bay with the EM3002 (multibeam echosounder) was planned and then implemented overnight. The detailed survey also collected sub-bottom profile (SBP) data (shallow penetration subsurface stratigraphic data), which, as collected ‘along-bay’ will complement existing cross-bay datasets and form a high resolution grid coverage pattern for full evaluation of the bay’s sediment stratigraphy. The ground-thruthing of this potentially exceptional data set could be achieved by follow-up vibrocoring studies.

As the area contains surface pockmarks (possibly gas seepage related) and (from existing and new SBP data) a buried channelised (high energy flows?) system, it will be of great interest to develop a full interpretation of the data to better understand the bay’s sedimentary dynamics.

The day ended with the development of plans to undertake side scan surveys and video transects of the pockmarked area known from previous studies.